Gravitational cooling and density profile near caustics in collisionless dark matter haloes

Mohayaee, Roya; Shandarin, Sergei F.

doi:10.1111/j.1365-2966.2005.09634.x

Cited by 37 publications

(49 citation statements)

References 44 publications

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“…We start our measurements at z = 3 and assume that the dark matter has undergone sufficient shell crossing before z = 3 that future caustics are not singular, and thus Eqs. (18)(19) are valid. To extrapolate backwards in time we use the time dependence found from z = 3 to z = 0 and assume it is valid earlier down to the initial conditions.…”

Section: B the Cumulant Hierarchy And Orbit Crossingmentioning

confidence: 98%

“…We use the N-body solution to measure the induced stress tensor generated by orbit crossing and calculate from it the corrections to the PPF predictions for the density and velocity divergence power spectra at large scales. Recent work on orbit crossing has concentrated on enhancement of dark matter annihilation in caustics [18,19,20]. We are instead interested on the impact of orbit crossing on the large-scale dynamics, outside dark matter halos.…”

Section: Introductionmentioning

confidence: 99%

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Generation of vorticity and velocity dispersion by orbit crossing

2009

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We study the generation of vorticity and velocity dispersion by orbit crossing using cosmological numerical simulations, and calculate the backreaction of these effects on the evolution of large-scale density and velocity divergence power spectra. We use Delaunay tessellations to define the velocity field, showing that the power spectra of velocity divergence and vorticity measured in this way are unbiased and have better noise properties than for standard interpolation methods that deal with mass weighted velocities. We show that high resolution simulations are required to recover the correct large-scale vorticity power spectrum, while poor resolution can spuriously amplify its amplitude by more than one order of magnitude. We measure the scalar and vector modes of the stress tensor induced by orbit crossing using an adaptive technique, showing that its vector modes lead, when input into the vorticity evolution equation, to the same vorticity power spectrum obtained from the Delaunay method. We incorporate orbit crossing corrections to the evolution of large scale density and velocity fields in perturbation theory by using the measured stress tensor modes. We find that at large scales (k ≃ 0.1 h Mpc −1 ) vector modes have very little effect in the density power spectrum, while scalar modes (velocity dispersion) can induce percent level corrections at z = 0, particularly in the velocity divergence power spectrum. In addition, we show that the velocity power spectrum is smaller than predicted by linear theory until well into the nonlinear regime, with little contribution from virial velocities.

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Section: B the Cumulant Hierarchy And Orbit Crossingmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Generation of vorticity and velocity dispersion by orbit crossing

2009

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“…Prospects for detecting gamma-rays have been discussed also for overdensities in DM halos called caustics (e.g. [292][293][294][295][296]). Much steeper profiles, called spikes, may form due to adiabatic growth of black holes, for example around the Super Massive black hole at the Galactic center (see e.g.…”

Section: Is It Compatible With Gamma-ray Constraints?mentioning

confidence: 99%

Dark matter candidates: a ten-point test

Taoso

Bertone

Masiero

2008

J. Cosmol. Astropart. Phys.

173

151

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An extraordinarily rich zoo of non-baryonic Dark Matter candidates has been proposed over the last three decades. Here we present a 10-point test that a new particle has to pass, in order to be considered a viable DM candidate: I.) Does it match the appropriate relic density? II.) Is it cold? III.) Is it neutral? IV.) Is it consistent with BBN? V.) Does it leave stellar evolution unchanged? VI.) Is it compatible with constraints on self-interactions? VII.) Is it consistent with direct DM searches? VIII.) Is it compatible with gamma-ray constraints? IX.) Is it compatible with other astrophysical bounds? X.) Can it be probed experimentally?

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“…DM caustics might occur within the first generation of halos. Caustics are not resolved in N-body simulations like the ones discussed here and might have significant effects on DM detection experiments (e.g., Mohayaee & Shandarin 2006).…”

Section: Introductionmentioning

confidence: 99%

Early Supersymmetric Cold Dark Matter Substructure

Diemand

Kuhlen

Madau

2006

ApJ

147

193

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Earth-mass ''microhalos'' may be the first objects to virialize in the early universe. Their ability to survive the hierarchical clustering process as substructure in the larger halos that form subsequently has implications for dark matter detection experiments. We present a large N-body simulation of early substructure in a supersymmetric cold dark matter (SUSY-CDM) scenario characterized by an exponential cutoff in the power spectrum at M c ¼ 10 À6 M . The simulation resolves a 0.014 M parent SUSY halo at z ¼ 75 with 14 million particles. On these scales, the effective index of the power spectrum approaches À3, and a range of mass scales collapses almost simultaneously. Compared to a z ¼ 0 galaxy cluster, substructure within our SUSY host is less evident both in phase-space and in physical space, and it is less resistant against tidal disruption. As the universe expands by a factor of 1.3, we find that between 20% and 40% of well-resolved SUSY substructure is destroyed, compared to only $1% in the low-redshift cluster. Nevertheless, SUSY substructure is just as abundant as in z ¼ 0 galaxy clusters; i.e., the normalized mass and circular velocity functions are very similar. The DM self-annihilation -ray luminosity from bound subhalos and other deviations from a smooth spherical configuration is at least comparable to the spherically averaged signal in the SUSY host, and at least 3 times larger than the spherically averaged signal in the cluster host. Such components must be taken into account when estimating the total cosmological extragalactic -ray annihilation background. The relative contribution of bound substructure alone to the total annihilation luminosity is about 4 times smaller in the SUSY host than in the z ¼ 0 cluster because of the smaller density contrast of micro-subhalos. Subject headingg s: early universe -large-scale structure of universe -methods: n-body simulationsmethods: numerical

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Gravitational cooling and density profile near caustics in collisionless dark matter haloes

Cited by 37 publications

References 44 publications

Generation of vorticity and velocity dispersion by orbit crossing

Generation of vorticity and velocity dispersion by orbit crossing

Dark matter candidates: a ten-point test

Early Supersymmetric Cold Dark Matter Substructure

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